Gadget Savvy: Capacitors Quiz

What looks like a battery, has two terminals like a battery and stores electrons like a battery? Capacitors can store and release electrical energy, but don't replenish their supply. How do capacitors work, and what tools rely on them?

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Question 1 of 10

What do capacitors store?

protons

electrons

In a way, capacitors are like batteries. Although they work in completely different ways, capacitors and batteries both store electrical energy in the form of electrons.

neutrons

Question 2 of 10

What separates the two terminals inside a capacitor?

metal

nonconductive material

Inside the capacitor, the terminals connect to two metal plates and are separated by a nonconducting substance, called a dielectric.

water

Question 3 of 10

What types of devices do air capacitors usually power?

radio tuning circuits

Mylar capacitors are commonly used for timing circuits, while ceramic ones are used for antennas. Air capacitors power radio tuning circuits.

timing circuits

antennas

Question 4 of 10

If you charge a capacitor using a 1.5-volt battery, how much voltage will the capacitor gain?

0 volts

1.5 volts

Once it's charged, the capacitor has the same voltage as the battery -- in this case, 1.5 volts.

3 volts

Question 5 of 10

Which of these is a natural example of a capacitor?

fire

snow

lightning

Nature shows the capacitor at work in the form of lightning. One plate is the cloud, the other plate is the ground, and the lightning is the charge released between these two.

Question 6 of 10

What unit of measurement is used when referring to a capacitor's storage potential?

volts

farads

A capacitor's storage potential, or capacitance, is measured in units called farads.

coulombs

Question 7 of 10

What's the primary difference between a capacitor and a battery?

Capacitors can store more electrons than batteries.

Capacitors hold the same amount of power as batteries, just in a smaller volume.

Capacitors can drain their electrons faster than batteries.

The difference between a capacitor and a battery is that a capacitor can dump its entire charge in a fraction of a second, whereas a battery would take minutes to completely discharge.

Question 8 of 10

Is a camera's electronic flash powered by a battery or a capacitor?

battery

capacitor

A camera's electronic flash uses a capacitor. The battery charges up the flash's capacitor over several seconds, and then the capacitor dumps the full charge into the flash tube almost instantly.

neither

Question 9 of 10

Why are charged capacitors dangerous?

They can leak harmful chemicals.

They can cause loss of vision.

They can release a lethal charge.

Large, charged capacitors are extremely dangerous, which is why flash units and TVs have warnings about opening them up. These products contain big capacitors that can, potentially, kill you with the charge they contain.

Question 10 of 10

What invention is generally referred to as the first capacitor?

Leyden jar

Records indicate that a German scientist named Ewald Georg von Kleist invented the capacitor in November 1745. Several months later, Pieter van Musschenbroek, a Dutch professor at the University of Leyden, came up with a very similar device in the form of the Leyden jar, typically credited as the first capacitor.